1. Field of the Invention
The present invention generally relates to seismic exploration and more particularly to vibrating hole forming device in which a vertically elongated mounting pipe with attached rack gear is powered vertically by a hydraulically driven pinion earth's surface. A vibrating mechanism imparts vibration to the downward force exerted by the pinion gear and rack gear. Vibration is imparted to the pipe automatically when hydraulic pressure required to operate the pinion gear reaches a predetermined pressure such as when the point on the lower end of the pipe encounters a predetermined resistance to further downward movement. This enables a lightweight unit to impart a constant downward force and a vibration force when needed to enable the device to penetrate through sands or extremely dense subsurface terrain thereby eliminating the necessity of providing a heavy weight vehicle such as is required when conventional hole forming devices are employed.
2. Description of the Prior Art
As is well known, seismic exploration of underground formations is conducted by positioning a plurality of explosive seismic charges below ground level at a designated depth and in designated pattern with these charges being subsequently detonated to produce seismograph recordings which can be analyzed to determine the character of the underground formation including whether the underground strata includes potentially recoverable oil or gas deposits and the like. Various devices have been provided to form vertical bores or holes in the earth's surface in which seismic charges are placed. Seismic exploration is necessarily conducted in locations having difficult access and terrain characteristics which are difficult to traverse. Various types of vehicles are utilized to convey seismic exploration equipment to an exploration site. Such vehicles are necessarily relatively heavy in order to provide a downward force on drilling or other earth penetrating equipment used to form vertical holes or bores in the earth to receive the explosive seismic charges. The necessity of making such vehicles heavy also introduces additional problems of gaining access to an exploration site. The following U.S. Pat. relate to this field of endeavor and include vibrating devices to assist in forming bore holes.
U.S. Pat. No. 3,394,766 PA1 U.S. Pat. No. 3,920,083 PA1 U.S. Pat. No. 4,471,669 PA1 U.S. Pat. No. 4,553,443 PA1 U.S. Pat. No. 4,819,740
While the above patents disclose vertically elongated members having vibration characteristics imparted thereto, none of the above patents disclose a vibrating mechanism associated with an elongated vertical pipe and rack gear attached thereto combined with a driven pinion gear which will force the pipe, which has a point on the lower end, into the earth and automatically impart vertical vibration to the pipe, rack gear and point when a predetermined resistance to downward penetration of the underground formation is encountered.